1. Field of the Invention
The present invention relates to a xenon light fixture. More particularly, but not by way of limitation, the present invention relates to a xenon light fixture having an integral ballast and a remote control.
2. Background of the Invention
Continuous arc xenon bulbs provide bright, stable, daylight balanced light at power levels from a few watts up to tens of thousands of watts. Such bulbs are widely accepted in architectural, entertainment, and medical applications. Typically, such bulbs require a moderate DC voltage (on the order of 18 to 150 volts) at a relatively high current for steady-state operation. In addition, a higher voltage is usually provided for starting (usually between 2 and 10 times the operating voltage) along with a very high voltage, short duration ignition pulse (on the order of several kilovolts for a period ranging from a few microseconds to a few milliseconds). Thus, a ballast or power supply is normally required for operation of a xenon bulb.
Presently, xenon power supplies may be logically divided into two distinct groups: a) those that operate at line frequency, otherwise known as magnetic ballasts; and b) those that operate at higher frequencies, commonly referred to as electronic power supplies. It should be noted that the terms xe2x80x9cballastxe2x80x9d and xe2x80x9cpower supplyxe2x80x9d are often used interchangeably. Magnetic ballasts typically employee a transformer followed by a rectifier and filter capacitors to provide the steady-state electrical power, much like a conventional linear power supply. Magnetic ballasts rely on the inductance of the transformer, or a separate inductor in series with the transformer, to limit the current provided by the ballast. The inductance of the ballast is such that, at the frequency of the AC power supplied to the ballast, the impedance limits the current through the bulb. This leads to ballasts which are characteristically large and heavy compared to their electronic counterparts.
Electronic power supplies, on the other hand, typically rectify and filter the incoming electrical power. Solid state switches such as transistors, MOSFETs, IGBTs, or the like, are used to xe2x80x9cchopxe2x80x9d the resulting DC voltage at a relatively high frequency, typically somewhere between 10 kilohertz and 100 kilohertz. This allows the use of inductors having a substantially lower inductance and hence, having a substantially smaller size. In addition, the DC voltage produced from this high frequency power may be filtered with smaller capacitors, also reducing the size of the power supply. For a number of reasons, these factors are particularly significant in the selection of a ballast for use in the entertainment industry. For example, magnetic ballasts often produce xe2x80x9cripplexe2x80x9d at the line frequency or, perhaps, at twice the line frequency. In the United States, this results in 60 Hz or 120 Hz flicker. When a filmed scene is lighted with a xenon powered by such a ballast, xe2x80x9cbeatingxe2x80x9d between the motion picture frame rate and the flicker can result in flicker at a slower, perceivable rate in the recorded images. In addition, flicker at any rate will totally preclude the use of frame rates higher than the flicker rate. Furthermore, magnetic ballasts designed for the power levels typically used in filing are often too heavy to be moved manually and therefore require undue time and labor for setup and tear down. Ideally, when the size and weight of the ballast allow, a ballast or power supply will be self-contained within a xenon light fixture so that a user merely xe2x80x9cplugs inxe2x80x9d the light and turns a switch on. Presently, xenon lights are available for the motion picture industry with integral ballasts up to about 10,000 watts. While such lights fill number of needs, i.e., easy setup and tear down, ease of use, negligible flicker or extremely high flicker rates, etc., these lights still suffer from a few remaining limitations, although such limitations are not necessarily unique to fixtures with integral ballasts.
Typically, such xenon lights are provided with a number of controls such as focus, on/off switching, dimming, and the like. When a light is suspended from rafters or catwalks, lifted with a crane, or otherwise placed in a relatively inaccessible position, it becomes inconvenient, or maybe even impossible, to operate the controls.
In addition, in some installations it is advantageous to know a number of environmental factors and performance characteristics of the light, such as ripple voltage which may cause the light intensity to vary, power output of the light which might affect camera settings, ambient and internal temperatures which may impact light performance, atmospheric pressure which can change the starting characteristics of the light, and attitude of the fixture.
Finally, a need exists for controlling such lights via an industry standard digital bus such as DMX-512, or the like. In particular, the bulb on/off, focus, and dimming controls are well suited for remote manipulation by way of an industry standard interface.
It is thus an object of the present invention to provide a xenon power supply with a remote control for controlling at least the on/off function of the bulb and focusing of the light beam.
It is still a further object of the present invention to provide a monitor which monitors and displays environmental and performance factors which may affect operation of the light.
Finally, it is yet a further object of the present invention to provide an industry standard interface for remote control of the light with commercially available equipment.
The present invention provides a xenon light fixture with integral ballast and a remote control. In one embodiment, circuitry supervises the remote control functions and monitors and displays environmental factors and performance characteristics which could potentially affect the light output of the bulb.
In a preferred embodiment, circuitry is provided which, among other things, monitors the incoming voltage and current, the output voltage and current to the bulb, the ambient temperature, the exhaust temperature which is representative of the internal temperature of the fixture, the atmospheric pressure, and the attitude of the fixture. The collected measurements are displayed on an LCD display, or the like, located on the fixture. When a measurement indicates a problem with the light or the use of the light, an appropriate alarm is triggered or the light is disabled. In addition, circuitry is provided to allow remote operation of the functions provided on the fixture (i.e., lamp on/off, focus, and dimming) either with a wired remote control or by way of a standardized interface such as DMX-512. Finally, accelerometers are provided, along with non-volatile memory, so that mishandling of the light may be recorded and recalled later to aid in servicing faulty fixtures or to identify the cause of broken equipment.
In another embodiment, relays are provided, with contacts either in series or parallel with switches, as appropriate, to provide alternate means for activation or deactivation of various functions provided on the fixture. A remote control allows the relays to be selectively energized or de-energized remotely by an operator. Thus, the lamp may be turned on or off, the focus manipulated, and dimming of the bulb controlled, even when access to the fixture is difficult or impossible.
Further objects, features, and advantages of the present invention will be apparent to those skilled in the art upon examining the accompanying drawings and upon reading the following description of the preferred embodiments.